1. Field of the Invention
The present invention relates to a capacity-controlled scroll-type compressor having an internally-bypassing system.
This application is based on patent applications Ser. Nos. Hei 9-363832, Hei 9-363833, and Hei 9-363834 filed in Japan, the contents of which are incorporated herein by reference.
2. Description of the Related Art
In conventional capacity-controlled scroll-type compressors having an internally-bypassing system, when the capacity of the compressor is controlled, a temperature difference occurs between an area through which higher-temperature bypassing gas passes and another area through which lower-temperature suction gas passes. Therefore, a gap at a tip provided on the head of each tooth near a gas-suction inlet tends to decrease and thus scuffing occurs.
On the other hand, when the capacity of the compressor is controlled, the temperature of a portion of scrolls, which is close to the main stream of higher-temperature bypassing gas, is higher than the temperature of other portions. Therefore, the teeth of the higher-temperature portion is extended, thereby decreasing a gap at a tip of the teeth and also generating scuffing in this case.
An object of the present invention is to solve the above problem related to scuffing due to decrease of such a tip gap.
Therefore, the present invention provides a capacity-controlled scroll-type compressor having an internally-bypassing system, the compressor comprising a housing, scrolls, and a gas-suction inlet, wherein the gas-suction inlet is positioned at the low-pressure side inside the housing; and the length of teeth of a portion of the scrolls, which is closer to the gas-suction inlet, is shorter than teeth of other portions of the scrolls.
According to this structure, when the capacity is controlled, it is possible to prevent the tip gaps near the gas-suction inlet from becoming smaller than those of other portions; thus, scuffing can be prevented between the heads of the target spiral lap and the inner surface of an end plate in the compressor.
The present invention also provides a capacity-controlled scroll-type compressor having an internally-bypassing system, the compressor comprising scrolls, wherein the length of teeth of a portion of the scrolls, which is close to the main stream of a bypassing gas, is shorter than teeth of other portions.
According to this structure, when the capacity is controlled, it is possible to prevent the tip gaps near the main stream of a bypassing gas from becoming smaller than those of other portions; thus, scuffing can be prevented between the heads of the target spiral lap and the inner surface of an end plate in the compressor.
In the above structures, the target portion for shortening the teeth may be of a hardening-processed scroll of the above scrolls
The present invention also provides a capacity-controlled scroll-type compressor having an internally-bypassing system, the compressor comprising a gas-suction inlet positioned near the main stream of a bypassing gas so as to suppress increase in the temperature of an area neighboring the main stream of the bypassing gas.
Also in this arrangement, when the capacity is controlled, it is possible to prevent the tip gaps near the main stream of a bypassing gas from becoming smaller than those of other portions; thus, scuffing can be prevented between the heads of the target spiral lap and the inner surface of an end plate in the compressor.